<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            padding: 0px;
            margin: 0px;
        }

        .left-div {
            float: left;
            width: 200px;
            /* 占100%的可视区域高度 */
            height: 100vh;
            background-color: #ffff00;
            box-sizing: border-box;
        }

        .right-div {
            float: left;
            background-color: #00ffff;
            height: 100vh;
            /* 宽度100% - 200像素 */
            width: calc(100% - 200px);
            box-sizing: border-box;
        }

        .main {
            height: 800px;
        }
    </style>
</head>
<body>
    <main class="main">
        <!-- 左侧宽200像素，占满整个高度 -->
        <aside class="left-div"></aside>
        <!-- 右侧占满余下所有宽度，占满整个高度 -->
        <section class="right-div"></section>
    </main>
</body>
</html>